For purposes of carrying out machining, polishing, buffing and other operations on items of metal or plastic or the like, it has long been known to place such a work piece in an ordinary work shop vice so that the piece may be held rigidly in place while the surface of such piece is worked upon. A vice may also be used to hold an item that has already been worked upon, e.g., items that have been glued together may be placed in a vice so as to maintain their fixed relationship while the glue hardens, or an item that has been painted may be held while the paint dries, and so on. Often, however, it is necessary to carry out machining and the other types of operations already mentioned on a large number of such items in sequence, and it then becomes tedious to place each item within a vice, tighten down the vice to hold the item in place, carry out the operation, loosen the vice so as to remove the item, and then replace that item with another similar item for a like operation.
Recognizing the inefficiency of the process just described, it has also long been known to provide a vice that has been adapted to accommodate at once a number of similar work pieces. In lieu of the usual vice that simply has two flat jaws facing one to the other, one of such jaws may be modified to include a number of cavities along the face thereof, said cavities being of a size and shape to accommodate insertion therein of a corresponding number of units of a particular type of work piece. An example of this procedure is shown in FIG. 1, wherein vice jig 10 is seen to comprise a first jaw 12 that has a simple flat surface, and facing thereon a second jaw 14, the side of which that faces onto first jaw 12 having been provided with a number of cavities 16 sized and shaped to accommodate a number of work pieces 18. Such work pieces will then be held in place upon movement of first and second jaws 12, 14 in the directions of arrows 20, 22, respectively.
(For purposes of clarity in the drawing, the top-most cavity 16 in FIG. 1 is shown without an included work piece 18. Also, although the shapes of cavities 16 and work pieces 18 are shown in FIG. 1 to be circular for ease of illustration, those shapes may be rectangular or any other such shape wherein some particular shape of cavity 16 has been designed to accommodate a particular kind of work piece 18.)
For many operations that are relatively undemanding, the apparatus of FIG. 1 as described to this point may serve quite well. However, for carrying out more precise operations such a procedure may be inadequate. For example, in the fabrication of second jaw 14 the precise dimensions of the several cavities 16 may not be identical. The individual dimensions of particular work pieces 18 may likewise not be exactly the same. In that case, the apparatus as described so far will not be able to hold a multiplicity of work pieces 18 under a pressure that is the same for each. Such an effect will come about if the combination of dimensions of cavity 16 and work piece 18 vary too much from one location to another along second jaw 14.
Thus, a particular work piece 18 may be held so loosely that it will become ejected when an attempt is made to work on it. Conversely, a pressure that would adequately hold a smaller work piece 18 within a slightly over-sized cavity 16 might inflict actual physical damage upon a neighboring and slightly larger work piece 18 that happened to have been placed within an under-sized cavity 16. Some means for equalizing the pressure on work pieces 18 of varying sizes that are to be held within cavities 16 that may also vary in sizes is required.
For that purpose, it has long been one practice to approximate such an equalizing effect by placing a strip 24 within vice jig 10 so as to face onto the interior surface of first jaw 12 and onto the facing surfaces of work pieces 18. Strip 24 may variously constitute a piece of leather, rubber, blotting paper, cloth, or any other such flexible material that is also resilient and can serve to assist in holding work pieces 18 under a pressure that may be at least somewhat more equal than would be the case in the absence of strip 24. Such a make-shift procedure can become inconvenient, however, since a worker must somehow manage to hold the several work pieces 18 in place while simultaneously installing strip 24 and closing first and second jaws 12, 14 together. The numerous ways in which strip 24 might happen to have become placed will also render it quite uncertain whether the desired effect of equalizing the strength with which the various work pieces 18 are held will actually have been produced.
With regard to single work pieces, and particularly those that may be irregular in shape, it is known to provide means by which such a piece can be held under essentially constant pressure along the full length thereof. That is, U. S. Pat. No. 1,453,176 issued Apr. 24, 1923 to Perrine describes a compensating jaw which includes a number of rods set in a row and leading through a corresponding number of channels to an elongate cavity containing an enclosed fluid. By virtue of the hydrostatic pressure exerted by such fluid, when such jaw is forced against an object of irregular shape, the respective rods each acquire an extension outwardly from the jaw for which that hydrostatic pressure will be equalized, i.e., the several rods may become extended to different distances in accordance with the shape of the object being held, but the pressure on each rod (and hence the pressure by which the work piece is held at that corresponding point) will be the same. However, no such device seems to have been developed that could accommodate a multiplicity of similar work pieces of varying size. What is needed and would be useful, therefore, is a device that could hold a multiplicity of items under such an equal pressure.